Imoen or Nalia?

At the start of BG2 Imoen gets taken away from you but there is an immediately available like-for-like replacement in Nalia. Personally I regard Nalia as a cut-price, bargain basement, cheap imitation of Imoen but because I generally play a good character I usually end up with her in my party - at least until I can get my little sister back and replace Nalia with someone else.

But what about the rest of you? Imoen? Nalia? Both? Neither?